On the inside of the left crank there is a small ring. The picture shows where the ring is meant to go.

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The ring is smooth / flat on one side. The picture shows the flat side which seems to have been rubbed silver by friction. The flat side seems to be made of metal.

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The other side has a raised ridge on the inner circumference. The raised ridge has a rubber/ plastic feel.

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What is the correct way to install this ring?

(Please excuse the low resolution images. It's the best this phone can do.)


It's possible that I previously installed this ring the wrong way and that's perhaps why the one side is polished. The ring seems to fit best with the ridged-side towards the bearing.

  • 1
    Not an answer but logic would say: friction polished side towards bearing. – Carel Jan 9 at 19:33
  • 1
    The exploded view of an octaink crank from the Shimano Manuals and Technical documents website (si.shimano.com/#) just show a washer flat on both sides. The drawings here are not super high quality but...and a couple "Dealer's Manuals" do not reference this aspect at all. The right side should also have a washer undernealth the fixing bolt. Perhaps check the shape and direction of this one you have. – Jeff Jan 11 at 5:23

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